Heart Care

Extra Sleep May Decrease Calcium Deposits in Arteries

A good night's sleep may be just what your arteries need, says a report in the Journal of the American Medical Association.

A new five-year study finds that middle-aged people who slept an extra hour each night were less likely to have artery-stiffening calcium deposits.

But the study results should not send people off to bed prematurely or have them taking sleeping pills, cautions study leader Dr. Diane Lauderdale, at the University of Chicago Medical Center.

"We don't know why there is an association," says Dr. Lauderdale. "And until we know why, we can't tell whether it is a causal association."

Dr. Lauderdale and her colleagues have been following a group of young adults for years as participants in an ongoing heart study.

Calcification Decreases by One-Third

The latest report links the sleeping habits of 495 participants, ages 35 to 47, with the incidence of artery calcification, measured by CT scans.

Calcium deposits can make the coronary arteries less flexible and ultimately lead to heart disease.

None of the participants had detectable calcium deposits when the study began, but five years later, 61 (12.3 percent) did.

After adjusting for some potential risk factors, such as sex, race, and smoking habits, the researchers found that one more hour of sleep a night decreased the risk of calcification by a third. That is about the same as a 16.5-point reduction in blood pressure, the researchers say.

"Nothing came out of the study as appearing to explain the association," notes Dr. Lauderdale. But she believes there are three possible explanations.

One is that another factor, such as socioeconomic status, was responsible for the connection. The second is cortisol, a stress-related hormone associated with decreased sleep and increased calcification.

"Finally, sleep is related to blood pressure, and that is a coronary artery disease risk factor," explains Dr. Lauderdale. "It's possible that for people who were sleeping more, their 24-hour blood pressure was lower than their daytime blood pressure."

Sleep Needs Can Vary

Whatever the link, it was to be expected, says Dr. Kathy P. Parker, a sleep expert and dean of the University of Rochester School of Nursing.

"We know that sleep deprivation does alter the physiology of numerous body systems, so it is not surprising that another health problem, or symptom or sign, should be related to sleep length," says Dr. Parker.

"There is considerable variation in sleep needs," says Dr. Parker, and no formula exists to calculate the ideal amount of sleep needed for any given person. "On average, an individual needs between seven and eight hours of sleep. There is an increase in health problems with five hours or less or nine hours or more."

The best advice, says Dr. Parker, who is one of only five US nurses certified by the American Board of Sleep Medicine, is "go to bed at a regular time, wake up at a regular time, pay attention to whether you feel refreshed and alert during the day, [and] avoid too much caffeine and alcohol."

Dr. Parker says that sleeping pills are appropriate at certain times for acute psychological stress, jet lag, or for specific sleep disorders.

"It's really important to wait until this finding is confirmed in another study population," cautions Dr. Lauderdale. "Also, until we know the mechanism, it is premature to base clinical advice on this information."

Always consult your physician for more information.

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If you take naps, try to do so at the same time every day. For most people, a short mid-afternoon nap is most helpful.

Avoid sleeping pills or use them conservatively. Most physicians avoid prescribing sleeping pills for a period of longer than 3 weeks. Never drink alcohol while taking sleeping pills.

Reduce evening light exposure by turning off bright lights. This may help cue the body and mind for sleep.

Expose yourself to light (through windows or a timed lamp) 30 minutes before waking to prepare for getting out of bed.

Make your bedroom cool, dark, and quiet. If possible, remove non-sleep related items such as televisions or computers so that the room is associated only with sleep.

People who suffer from insomnia that lasts for more than a few days should consult a physician so that the underlying cause can be identified and possibly related. If you have loud, irregular snoring, jerking legs, or pauses in breathing in addition to other symptoms of insomnia, seek the advice of a physician.

These symptoms may be related to sleep apnea, a potentially life-threatening condition. There are a variety of effective treatment options available.